By-pass valve for heat exchanger

ABSTRACT

A valve that includes a housing defining first and second bores having a central axis, and a peripheral valve seat. An actuator is located in the first bore and has a reciprocating seal disposed for movement along the central axis for engaging the valve seat and closing the valve. A coiled return spring is mounted in the housing for urging the reciprocating seal towards the chamber to open the valve, the return spring having a first end connected to the reciprocating seal and a second end engaging a spring support in the housing facing the first bore. The return spring may have a larger diameter at its second end than its first end. The housing may include a third bore in communication with the second bore and having a different cross-sectional area than the second bore. A closure cap formed from moldable material may close an opening in the housing, the closure cap being sealably joined to the housing by a welded joint. The return spring could be supported by a discrete spring support located in one of the bores. The valve seat and an annular sealing member may have corresponding sloping surfaces that cooperate when the sealing member engages the valve seat.

FIELD OF THE INVENTION

This invention relates to heat exchangers, and in particular, to by-passvalves for by-passing a heat exchanger in a heat exchange circuit underconditions where the heat transfer function of the heat exchanger is notrequired or is only intermittently required.

BACKGROUND

In certain applications, such as in the automotive industry, heatexchangers are used to cool or heat certain fluids, such as engine oilor transmission fluid or oil. In the case of transmission fluid, forinstance, a heat exchanger is used to cool the transmission fluid. Theheat exchanger is usually located remote from the transmission andreceives hot transmission oil from the transmission through supplytubing, cools it, and delivers it back to the transmission again throughreturn tubing. However, when the transmission is cold, such as atstart-up conditions, the transmission oil is very viscous and does notflow easily through the heat exchanger, if at all. In such cases, thetransmission can be starved of oil and this may cause damage or at theleast erratic performance. Cumulative damage to the transmission canalso occur if the quantity of oil returned is adequate, but isovercooled due to low ambient temperatures. In this case, for instance,moisture condensation in the oil (that would otherwise be vaporized athigher temperatures) may accumulate and cause corrosion damage or oildegradation.

In order to overcome the cold flow starvation problem, various solutionshave been proposed in the past. One solution is to use a by-pass pathbetween the heat exchanger supply and return lines often with aheat-actuated by-pass valve located in the by-pass path. There have beenshort-comings with many prior solutions, including for example,excessive leakage across the valve, sticking of the valve, heat transferinefficiencies, and/or high cost.

A by-pass valve configuration that addresses many of the short comingsof prior actuator valves is shown in U.S. Pat. No. 6,253,837.

However a by-pass valve having additional cost savings, space savings,weight savings and/or operational efficiencies is desirable for someapplications.

SUMMARY

According to at least one example aspect of the invention is a heatexchanger by-pass, including a housing defining communicating first andsecond bores therein and first and second main ports communicating withthe first bore, the second bore having a central axis and a peripheralvalve seat about a valve opening facing the first bore. A temperatureresponsive actuator is located in the housing and has a reciprocatingcentral shaft disposed along said central axis, the central shaft havinga closed end portion. An annular sealing member slidably mounted on thecentral shaft extends outward from the central shaft to engage the valveseat and, together with the closed end portion, close the valve opening.The by-pass valve includes bias means for urging the annular sealingmember toward the valve seat A coiled return spring is mounted in thehousing for urging the central shaft closed end portion to retract andopen the valve opening, the return spring having a first end connectedto the closed end portion and a second end engaging a spring support inthe housing facing the first bore. The return spring has a largerdiameter at its second end than its first end.

According to at least one example aspect of the invention is a valveincluding a housing defining a first bore and a second bore having acommon central axis and communicating with each other through a valveopening having a peripheral valve seat, the first bore, second bore andvalve opening forming at least a portion of a closable flow path betweena first opening and a second opening in the housing. An actuator locatedin the housing has a reciprocating seal disposed for movement along thecentral axis for engaging the valve seat and closing the valve opening.A coiled return spring is mounted in the housing for urging thereciprocating seal towards the first bore to open the valve opening, thereturn spring having a first end connected to the reciprocating seal anda second end engaging a spring support in the housing facing the firstbore, the return spring having a larger diameter at its second end thanits first end.

According to at least one example aspect of the invention is a by-passvalve for a heat exchanger circuit, including a housing defining aserially communicating first bore, second bore and third boresubstantially aligned along a central axis with a valve seat facing thefirst bore at a juncture between the first bore and second bore and aspring seat facing the second bore at a juncture between the second boreand third bore, the first bore, second bore and third bore forming atleast a portion of a closable flow path between a first opening and asecond opening in the housing. The by-pass valve also includes anactuator located in the housing and having a reciprocating seal disposedfor movement along the central axis for engaging the valve seat andclosing a valve opening between the first bore and second bore, and acoiled return spring mounted in the housing for urging the reciprocatingseal towards the first bore to open the valve opening, the return springhaving a first end acting on the reciprocating seal and a second endengaging the spring seat. The second bore and third bore each have adifferent cross-sectional shape transverse to the central axis.

According to at least one example aspect a by-pass valve for a heatexchanger circuit, the by-pass valve including a housing formed fromplastic material and defining a first bore with a valve openingcommunicating therewith, the valve opening having a peripheral valveseat facing the first bore, the housing defining an assembly openingcommunicating with the first bore opposite the valve seat, an actuatorlocated in the first bore and having a reciprocating seal disposed formovement along an axis for engaging the valve seat and closing the valveopening, and a closure cap formed from plastic material and closing theassembly opening, the closure cap being sealably joined to the housingby a permanent joint.

According to at least one example aspect of the invention is a methodfor making a by-pass valve for a heat exchanger circuit, including:providing a housing defining a first bore with a valve openingcommunicating therewith, the valve opening having a peripheral valveseat facing the first bore, the housing including an assembly openingopposite the valve seat; providing a closure cap; providing an actuatorhaving a reciprocating seal and inserting the actuator into the firstbore through the assembly opening so that the actuator is located in thefirst bore for movement along a central axis for engaging the valve seatand closing the valve opening; and permanently connecting the closurecap to the housing to seal the assembly opening.

According to at least one example aspect of the invention is a by-passvalve for a heat exchanger circuit, the by-pass valve including ahousing defining a communicating first bore and second bore with aperipheral valve seat located at a junction thereof about a valveopening, the first bore, second bore and valve opening forming at leasta portion of a closable flow path between a first opening and a secondopening in the housing. The by-pass valve includes an actuator locatedin the first bore and having a reciprocating seal disposed for movementto engage the valve seat and close the valve opening, a coiled returnspring mounted in the housing for urging the reciprocating seal towardsthe first bore to open the valve opening, the return spring having afirst end acting on the reciprocating seal, and a second end. A discretespring support extends across the second bore and has a surfacesupporting the second end of the return spring, the spring supportincluding at least one fluid flow opening there through for fluidflowing through the valve opening.

According to at least one example aspect of the invention is a by-passvalve for a heat exchanger circuit, the by-pass valve including ahousing defining first and second bores aligned along a central axis andcommunicating through a valve opening surrounded by a peripheral valveseat, the first bore, second bore and valve opening forming at least aportion of a closable flow path between a first opening and a secondopening in the housing. The by-pass valve also includes a temperatureresponsive actuator located in the first bore and having a reciprocatingcentral shaft disposed along said central axis, the central shaft havinga closed end portion, an annular sealing member slidably mounted on thecentral shaft and extending outward from the central shaft to engage thevalve seat and, together with the closed end portion, close the valveopening, bias means for urging the annular sealing member toward thevalve seat, and a coiled return spring mounted in the housing for urgingthe central shaft closed end portion to retract and open the valveopening, the return spring having a first end connected to the closedend portion and a second end engaging a spring support in the housingfacing the first bore. The valve seat and the annular sealing memberhave corresponding sloping surfaces that cooperate when the sealingmember engages the valve seat.

According to at least one example aspect of the invention is a by-passvalve for a heat exchanger circuit, the by-pass valve including ahousing formed from a plastic material and defining a first bore with avalve opening communicating therewith, the valve opening having aperipheral valve seat facing the first bore, the housing defining anassembly opening communicating with the first bore opposite the valveseat, the first bore and valve opening forming at least a portion of aclosable flow path between a first opening and a second opening in thehousing; an actuator located in the first bore and having areciprocating seal disposed for movement along an axis for engaging thevalve seat and closing the valve opening; and a closure cap formed fromresilient material and closing the assembly opening, the closure capbeing sealably mounted in a end of the upper bore adjacent the assemblyopening, the housing including surfaces between which the closure cap iscompressively engaged.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the invention will now be described withreference to the accompanying drawings, throughout which similarelements and features are denoted by the same reference numbers, and inwhich:

FIG. 1 is an elevational view, partly in cross-section, of a by-passvalve according to an example embodiment of the invention, showing theby-pass valve in an open position;

FIG. 2 is an elevational view, partly in cross-section, showing theby-pass valve in a closed position;

FIG. 3 is an elevational cross-section exploded view showing a housingand closure cap of the by-pass valve of FIGS. 1 and 2;

FIG. 4 is an elevational view of a valve assembly used in the by-passvalve of FIGS. 1 and 2;

FIGS. 5A-5D show views of a closure cap used in the by-pass valve ofFIGS. 1 and 2, wherein FIG. 5A is a perspective view, FIG. 5B is anelevational view, FIG. 5C is a bottom plan view, and FIG. 5D is asectional view taken along the line A-A of FIG. 5C;

FIG. 6 is a sectional view of the housing, taken along the line B-B ofFIG. 3;

FIG. 7 is an elevational view, partly in cross-section, of a by-passvalve according to a further example embodiment of the invention,showing the by-pass valve in an open position;

FIG. 8 is an elevational view, in cross-section, of a by-pass valveaccording to a further example embodiment of the invention, showing theby-pass valve in an open position;

FIGS. 9A and 9B are plan views each showing an example of a returnspring support member for use in the by-pass valve of FIG. 8;

FIGS. 10 and 11 are elevational views, in cross-section, each showing afurther example of a return spring support member for use in the by-passvalve of FIG. 8;

FIG. 12 is an elevational view, in cross-section, of a by-pass valvehaving a valve sealing configuration according to a further exampleembodiment of the invention, showing the by-pass valve in an openposition;

FIG. 13 is a plan view of an annular valve member used in the by-passvalve sealing configuration of FIG. 12;

FIG. 14 is a sectional view of the annular valve member, taken acrosslines C-C of FIG. 13;

FIG. 15 is an elevational view of a valve assembly having a furtherembodiment of a return spring;

FIG. 16 is a partial sectional view of a further embodiment of a capreceived in an upper end of the by-pass valve housing; and

FIG. 17 is an elevational view of the cap of FIG. 16.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Referring firstly to FIG. 1, there is shown a by-pass valve, indicatedgenerally by reference 14. By-pass valve 14 may be used in a heatexchanger circuit to control the flow a fluid to a heat exchanger 12, towhich first and second conduits 28 and 32 are connected. Conduits 28, 32are connected to inlet and outlet ports in by-pass valve 14 as will bedescribed further below. Conduits 34, 36 are also connected to ports inby-pass valve 14 as will be described further below. By-pass valve 14 isreferred to as a four port by-pass valve, because four conduits 28, 32,34 and 36 are connected to by-pass valve 14.

Referring now to FIGS. 1-4, the by-pass valve 14 has a housing 46 withserially communicating coaxial first bore 48, second bore 54 and thirdbore 55 therein. In an example embodiment, the housing 46 is formed of amoldable material such as a plastic material which may be athermoplastic or a thermosetting material and which may containreinforcement such as glass fiber or particulate reinforcement. Housing46 defines two main ports or openings 50, 52 communicating with thefirst bore 48. Third bore 55 has a smaller cross-sectional flow areathan that of second bore 54. First bore 48 communicates directly withsecond bore 54 which in turn communicates through third bore 55 with twoopenings or branch ports 56, 58. Conduits 28, 36 are connectedrespectively to the branch ports 56, 58. Conduits 32 and 34 areconnected to main ports 50 and 52, respectively. Ports 50, 52, 56 and 58may be internally threaded for receiving threaded end portions ofconduits 32, 34, 28 and 36, respectively, however the conduits and portscould alternatively be connected using other methods, including forexample molding the ports around the conduits.

Second bore 54 has a peripheral valve seat 60 facing first bore 48. Inthe illustrated embodiment, valve seat 60 is an annular shoulder formedabout valve opening 53 by housing 46 at a transition or junction betweenfirst bore 48 and second bore 54. A movable valve member 62 is adaptedto engage valve seat 60 to open and close valve opening 53. Atemperature responsive actuator 64 is located inside first bore 48 andis operably coupled to valve member 62 to move valve member 62 therebyopening and closing valve opening 53. Actuator 64 is sometimes referredto as a thermal motor and it is a piston and cylinder type devicewherein the cylinder is filled with a thermal sensitive material, suchas wax, that expands and contracts causing the actuator to extendaxially upon being heated to a predetermined temperature.

It will be seen from FIGS. 1-4 that actuator 64 is located along acentral axis of first bore 48 and second bore 54. In an exampleembodiment, coaxial first bore 48 and second bore 54 are both generallycylindrical, with second bore 54 having a smaller diameter than firstbore 48. The cylinder of actuator 64 forms a central shaft 66 disposedalong the central axis of first bore 48 and second bore 54. Centralshaft 66 has a closed end portion 68 that has a diameter less than thatof second bore 54 and which partially closes valve opening 53. Valvemember 62, which is in the form of an annular ring located adjacent toclosed end portion 68 in its normal or at rest position as indicated inFIG. 1, extends transversely from the central shaft 66 to engage valveseat 60 to close valve opening 53 as indicated in FIG. 2. The annularring 62 and closed end portion 68 form a reciprocating plug which movesalong the central axis to open and close valve opening 53. Annular ringor valve member 62 is slidably mounted on central shaft 66.

Third bore 55, which is coaxial with first bore 48 and second bore 54has a different cross-sectional flow area than second bore 54. In thepresently described example embodiment, the cross-sectional flow area ofthe third bore 55 is smaller than that of the second bore 54, such thatthe housing 46 defines a peripheral spring seat 69 facing the secondbore and first bore 48 at a junction or transition between the secondand third bores 54, 55. A return spring 70 has a first end 40 attachedto closed end portion 68 by being located in a groove (not shown) formedin closed end portion 68. The return spring 70 has a second end 42located in spring seat 69. Return spring 70 thus urges the central shaft66 away from valve seat 60 into its retracted position of FIG. 1, andacts as a stop for preventing annular ring 62 from sliding off centralshaft 66. As best seen in FIG. 4, the return spring 70 has a coildiameter that gets larger as the distance from end portion 68 increases,such that the return spring 70 tapers outward from first end 40 to thesecond end 42. In particular, the spring coil diameter at first end 40is sized to fit around closed end portion 68, and the spring coildiameter at second end 42 is sized about the same as the diameter ofsecond bore 54.

As will be apparent from FIG. 4, thermal motor 64, override spring 74,annular ring 62 and return spring 70 form a valve cartridge orsubassembly 38 for by-pass valve 14. As best seen in FIG. 4, centralshaft 66 includes an inner annular shoulder 72, and a override spring 74mounted on central shaft 66 between shoulder 72 and annular ring 62. Theoverride spring 74 urges or biases annular ring 62 toward the stop orreturn spring 70, and thus toward valve seat 60.

As best seen in FIG. 3, the first bore 48 includes an opening 81 thatopposes valve opening 53 and through which the valve assembly 38 of FIG.4 can be inserted into first bore 48 during assembly of the by-passvalve 14. A closure cap 80 is inserted into the opening 81 to seal thefirst bore 48 after the valve assembly 38 is in place. As with housing46, closure cap 80 may be formed from a moldable material such as aplastic material which may be a thermoplastic or a thermosettingmaterial and which may contain reinforcement such as glass fiber orparticulate reinforcement. The closure cap 80 is in at least one exampleembodiment ultrasonically welded to the housing 46 to form a secureseal.

Thermal motor or actuator 64 has a piston 76 (see FIG. 4) that isattached or fitted into an axial recess 78 (see FIG. 3) formed inclosure cap 80. As will be described in more detail below, when thermalmotor 64 reaches a predetermined temperature, it extends axially. Sincepiston 76 is fixed in position, central shaft 66, which is part ofthermal motor 64, moves downwardly through second bore 54 compressingreturn spring 70 and closing valve opening 53. When the temperatureinside first bore 48 drops below the predetermined temperature, thermalmotor 64 retracts and return spring 70 urges central shaft 66 upwardlyuntil return spring 70 engages annular ring 62 and lifts it off valveseat 60 again opening valve opening 53. When valve opening 53 is openedas indicated in FIG. 1, return spring 70 extends through second bore 54and partially into first bore 48.

The operation of by-pass valve 14 will now be described with referenceto FIGS. 1-4. The heat exchange circuit in which the valve 14 is usedcan be operated with either conduit 34 or conduit 36 being the inletconduit, the other one being the outlet conduit. Where conduit 34 is theinlet conduit, or in other words, receives hot transmission oil from thetransmission, this is sometimes conveniently referred to as forwardflow. In this case, conduit 36 is the outlet conduit and returns thetransmission oil to the transmission after it has been cooled by heatexchanger 12.

Where conduit 36 is the inlet conduit receiving the hot transmissionfluid or oil from the transmission and conduit 34 is the outlet orreturn conduit for delivering the cooled oil back to the transmission,this configuration is sometimes conveniently referred to as reverseflow.

Dealing first with the forward flow configuration, if the transmissionoil and heat exchange circuit 10 have been warmed up to operatingtemperatures, by-pass valve 14 appears as in FIG. 2. Hot engine oilenters into inlet conduit 34, passes in series through main port 52,first bore 48 and main port 50 to heat exchanger inlet conduit 32. Thehot fluid passes through heat exchanger 12 and returns through outletconduit 28, passes through branch ports 56, 58 and out through outletconduit 36 to return to the transmission. In this case, there issubstantially no by-pass flow, because valve opening 53 is closed. Ifthe fluid returning to the transmission through conduits 28, 36 dropsbelow a predetermined temperature, by way of non-limiting example about80 degrees C., actuator 64 retracts causing valve member 62 to lift offvalve seat 60 opening valve opening 53, as in FIG. 1. This creates aby-pass flow from conduit 34 through first bore 48 and through valveopening 53 to join the flow in conduit 36 returning to the transmission.If the temperature of the flow or oil is very cold, such as at enginestart-up conditions, the oil may be so viscous that virtually no flowgoes through heat exchanger 12 and the flow is totally by-passed frominlet conduit 34 to outlet conduit 36. As the oil starts to warm up,however, flow through conduit 32 and heat exchanger 12 starts toincrease, and by the time the oil reaches the desired operatingtemperature, full flow is occurring through heat exchanger 12 and valvemember 62 closes valve opening 53 discontinuing the by-pass flow. Itwill be appreciated that when by-pass valve 14, or at least valve member62, is open main ports 52 and 50 become respective inlet and outletports in this forward flow configuration. In the forward flowconfiguration, one of the branch ports, namely branch port 56 becomes aninlet port, and the other branch port 58 thus becomes an outlet portcommunicating with inlet port 56.

In the reverse flow configuration, conduit 36 becomes the inlet conduitreceiving hot oil from the transmission, and conduit 34 becomes theoutlet conduit returning the cooled transmission oil to thetransmission. In this configuration, if the transmission and heatexchange circuit 10 are at operating temperatures, the hot transmissionfluid passes through branch port 58, which becomes an inlet port. Valvemember 62 is closed so there is no by-pass flow. The hot oil thencontinues on through branch port 56 which becomes an outlet portcommunicating with inlet branch port 58. The hot oil goes throughconduit 28 and the heat exchanger 12 and returns through conduit 32 topass in series through second main port 50, first bore 48 and third mainport 52 and out through conduit 34 to be returned to the transmission.

If the transmission oil returning to the transmission drops below thepredetermined temperature, actuator 64 causes valve member 62 to opencreating by-pass flow from valve opening 53 to main port 52 and conduit34. Again, if the oil is extremely cold, such as at engine start-upconditions, very little, if any, flow passes through heat exchanger 12and there is almost total by-pass through by-pass valve 14. As thetransmission oil starts to warm up, some flow starts to go through heatexchanger 12 and returns through conduit 32 to first bore 48 and back tothe transmission through conduit 34. This causes actuator 64 to warm upfaster than would otherwise be the case. As the transmission oilreturning to the transmission through outlet conduit 34 reaches thepredetermined temperature, actuator 64 extends closing valve member 62and stopping the by-pass flow. In this configuration, any pressure peaksthat might occur upon the closing of valve member 62 are attenuated ormodulated, because valve member 62 can lift off valve seat 60 by such apressure surge, since valve member 62 is urged into position by overridespring 74 and not solidly in engagement with valve seat 60. In otherwords, override spring 74 can absorb pressure spikes in inlet conduits36, 28, so that they do not travel back and adversely affect thetransmission. The circuiting of the valve is such that the housingfunctions as a mixing chamber, in which the by-pass fluid stream and theheat exchanger outlet stream can mix in direct contact with the thermalactuator, so that thermal transients are damped, and the actuator isable to directly respond to the mixed oil temperature being returned tothe transmission. Also during the transition between opening andclosing, the hot by-pass stream and cooler oil cooler return stream aremixed (as controlled by the directing contacting actuator 64) to dampenany temperature transients in the oil being returned to thetransmission.

In the reverse flow configuration, main ports 50, 52 become respectiveinlet and outlet ports for by-pass valve 14.

As actuator 64 is located in first bore 48 with oil continuously flowingtherethrough, actuator 64 warms up and cools off quickly. Also, if thetransmission oil becomes over-heated or experiences a temperature spike,actuator 64 is not damaged, because it will normally be exposed to somereturn flow from heat exchanger 12 in first bore 48 in the reverse flowconfiguration, or in branch ports 56, 58 in the forward flowconfiguration. Further, if actuator 64 is overheated and tends to expandtoo far, it will not be damaged, because central shaft 66 can extendthrough second bore 54 as required.

Having described the overall configuration and operation of an exampleembodiment of the by-pass valve 14, particular features of the by-passvalve will now be described in greater detail.

Turning to FIG. 3 and FIGS. 5A-5C, in the illustrated embodiment, cap 80defines an outer cylindrical wall 90 sized to fit in the upper end offirst bore 48, and a larger diameter disk-like head 92. First bore 48has a cap seat 94 formed about a circumference of opening 81 in whichenlarged cap head 92 is located. As illustrated, the axial recess 78(which receives an end of thermal motor piston 76) is defined by aninner cylindrical wall 96 that is radially spaced from externalcylindrical wall 90. A series of uniformly spaced radial webs 100 extendbetween inner and outer walls 96, 90. An annular groove 102 (FIG. 5B)may be formed in an outer surface of the outer cylindrical wall 90. Asnoted above, cap 80 can be ultrasonically welded to housing 46 in orderto seal the opening 81 of first bore 48, providing a light weight,inexpensive and durable means for sealably closing assembly opening 81of the first bore 48 which, in at least some applications, will notrequire an additional seal such as an O-ring, and/or will not require anaddition retaining member such as a C-clip. Although the presentlydescribed cap provides certain advantages, in some embodiments plasticcap 80 could be replaced with a metal cap having an annular sealingring, and/or could be secured in place through some other non-permanentmeans such as, for example, with a C-clip, or by being threaded, orhaving a twist lock configuration, rather than through ultrasonicwelding. Furthermore, a permanent leak resistant joint between the cap80 and housing 46 could be formed by methods other than ultrasonicwelding, such as by friction welding, or through chemical bonding.Chemical bonding could include the use of an intermediate adhesive orsolvent bonding in which a solvent is used to temporarily disolvecooperating surfaces that then join together, thereby providing abonding effect similar to ultrasonic or friction welding. Additionally,the cap 80 may be used with housing and valve assembly combinations thatare different from that shown in the Figures and described herein.

With reference to FIGS. 3 and 6, third bore 55 will now be discussed ingreater detail. As indicated above, the second bore 54 communicates withbranch ports 56 and 58 through third bore 55, with peripheral springseat 69 facing second bore 54. The third bore 55 in combination withperipheral spring seat 69, allows the return spring 70 to be supportedabove the internal passage through housing 46 that is provided bycooperating and coaxial branch ports 56 and 58, thereby providingunimpeded flow between the branch ports 56 and 58. Spring seat 69 isdefined by housing 48 as a result of the reduction in cross-sectionalflow area between the second bore 54 and the third bore 55. As notedabove, second bore 54 is cylindrical, and thus has a circularcross-sectional flow area transverse to its axis. In an exampleembodiment, the third bore 55 has a non-circular cross-sectional flowarea, and in particular, as seen in FIG. 6, the third bore 55 has arectangular cross-sectional area along its length. Thus, the size of thespring seat 69 varies about the periphery of the third bore 55. The useof a third bore 55 having a non-circular cross-section allows the flowarea of the third bore 55 to be maximized, while at the same timeproviding a stable seat 69 for return spring 70. Such a non-circularconfiguration may be particularly advantageous in embodiments where thecoil diameter of the return spring 70 does not increase towards thespring seat 69, in which case a spring seat extending further inwardfrom the outer circumference of the wall defining second bore 54 wouldbe required. Instead of being rectangular, other non-circularcross-sectional configurations could be used, for example othermulti-sided configurations such as square or polygon, or curvedconfigurations such as elliptical, could be employed.

In some embodiments, third bore 55 may be cylindrical with a circularcross-sectional area. For example, when third bore 55 is used incombination with an outwardly tapering return spring 70, in someapplications a non-circular third bore 55 may not offer that substantialan advantage over a circular third bore 55. However, in otherapplications, the increased flow permitted by a non-circular third bore55 may be highly advantageous.

In some embodiments, spring seat 69 may be provided by means other thana transition between second bore 54 and a cooperating coaxial third bore55. For example, the second and third bores could be replaced with asingle bore having a substantially uniform diameter along its entirelength, and spring seat 69 could be accomplished by an inwardlyextending ring formed on the wall of the bore 54 or 55 about opening 53,or by other inward projections formed on the wall of the bore 54 or 55.

With reference again to FIGS. 1-4, tapered return spring 70 will now bediscussed in greater detail. As will be appreciated from the abovedescription, the piston or central shaft 66 of valve assembly 38 has asmaller diameter than second bore 54 so that closed end portion 68 canextend into second bore 54, and also to facilitate fluid flow around theshaft 66 when valve member 62 is not in valve seat 60. Thus, the firstend 40 of return spring 70 that is attached to end portion 68 will alsohave a smaller diameter than the second bore 54. As indicated above, thediameter of the successive coils of the return spring 70 increase fromthe first end 40 to the seat engaging second end 42, such that thediameter of the second end 42 is substantially the same as or close tothe inner diameter of second bore 54. Such a spring configuration canprovide a number of advantages. For example, having a second end 42diameter that is the same or close to the same size as the second borediameter provides a self-centering and self locating feature and assistsin positioning the spring in the valve opening 53 and maintaining thesecond end 42 in correct alignment with spring seat 69, thereby allowinga smaller spring seat 69 (and hence larger third bore 55) to be usedthan might otherwise be required if a return spring of uniform coil sizewere employed. The spring 70 may also assist in centering the valveassembly 38, including valve member 62, during operation of the by-passvalve. Additionally, the use of a spring of varying coil diameter allowsfor a greater distance between adjacent coils as the coils expand, asadjacent coils are not only axially spaced from each other (as in auniform diameter spring), but are also radially spaced from each other.Thus, there is increased area for fluid to flow through the coils of thetapered return spring 70 such that spring 70 offers less flow resistancethan a similar non-tapered return spring.

In some embodiments, as has been suggested above and will be explainedbelow, a spring of uniform diameter may be used in place of taperedspring 70. Additionally, in some embodiments, the tapered return spring70 may be used in combination with a by-pass valve having features otherthan those described above. For example, FIG. 7 shows a further exampleembodiment of an open by-pass valve 110, in which tapering return spring70 may be used. The by-pass valve 110 is similar in configuration andoperation to by-pass valve 14, with differences that will be apparentfrom the Figures and present description. By-pass valve 110 is atwo-bore design in that the third bore 55 is omitted. The second bore 54communicates directly with a branch port flow passage 112 formed bycoaxial and cooperating branch ports 56, 58. The valve seat 69 and valveopening 53 are located at the juncture between first bore 48 and secondbore 54. In such embodiment, the return spring 70 extends across passage112 and its second end 42 rests against a wall 114 of branch port flowpassage 112 that faces the first bore 48 and valve opening 53. In suchconfiguration, the tapering spring 70 offers less flow resistance inpassage 112 than a uniform diameter spring would.

Turning again to the by-pass valve configuration of FIGS. 1-4, in someembodiments branch ports 58 and 56 may be omitted, and the third bore 55may communicate directly with one of the conduits 28 or 36, in whichcase the by-pass valve would be a three port valve, with third bore 55being an inlet or outlet port to the by-pass valve. In such aconfiguration, whichever of the conduits 28 or 36 is not connected tocommunicate with third bore 55 will be connected to the other conduit 28or 36 at a location spaced apart from the by-pass valve.

As noted above, in some embodiments a uniform coil return spring may beused in place of a tapered return spring 70, and in this regardreference is now made to FIG. 8 which shows a further example embodimentof an open by-pass valve 120, in which a straight return spring 124 isused. The by-pass valve 120 is similar in configuration and operation toby-pass valve 14, with differences that will be apparent from theFigures and present description. In the present embodiment, theextending end of the uniform width return spring 124 is smaller than thethird bore 55 that communicates with second bore 54, and thus a discretespring support member 122, examples of which are shown in plan view inFIGS. 9A and 9B, is positioned in peripheral seat 69. Discrete supportmember 122, which may be formed from metal or plastic and/or othermaterials, is formed separately from housing 46 and positioned on seat69. In some example embodiments, the support member 122 may be connectedto the extending end of return spring 124 prior to the insertion ofvalve assembly 38 into the first bore 48. When the valve is assembled,the extending end of return spring 124 rests against the spring supportmember 122, and the other end of the return spring engages end portion68 of thermal motor shaft 66. Spring support member 122 can be acircular planar disk-like member with a series of flow openings 126formed therethrough. Support member 122 could take a number of differentconfigurations to fulfill its dual function of supporting spring 124while allowing fluid to flow through the support member, with FIGS. 9Aand 9B showing but two possibilities. In the by-pass valve configurationof FIG. 8, support member 122 allows third bore 55 to be larger than ifthe uniform width return spring 124 rested directly on seat 69 withoutthe support member. In some example embodiments, support member 122 maybe used in combination with a tapering return spring 70.

In at least one example embodiment, planar support member 122 isreplaced with a cup-like support member 122A, as shown in FIG. 10.Support member 122A includes an annular wall 130 having an outerperipheral flange 128 at one end thereof and a radially inwardlyextending flange 132 at an opposite end thereof. The outer flange 128sits on seat 69, the annular wall 130 extends into third bore 55, andreturn spring 124 is seated on inner flange 132. An axial flow opening126 is defined by flange 132. Annular wall 130 may be cylidrical, or maytaper inwards as the distance from seat 69 increases. In someembodiments, particularly in tapering embodiments, flow openings 134 mayextend through the annular wall 130.

In some embodiments, a further cup-like support member 122B, having aconfiguration substantially opposite that of support member 122A, isused in combination with seat 69 to support the return spring 124.Support member 122B includes an annular wall 136 having an outerperipheral flange 138 at one end and a shoulder defining a spring seat140 at an opposite end thereof. In use, the outer peripheral flange 138rests on seat 69, the annular wall 136 extends into the second bore 54and the second end 42 of return spring 124 rests in seat 140. The cupconfigurations 122A and 122B assist in locating and retaining returnspring 124.

Turning now to FIGS. 12-13 a further valve seat and valve membercombination that can be applied to any of the by-pass valves describedabove will now be explained in the context of by-pass valve 120. In FIG.12, the annular valve member 62 and it cooperating valve seat 68 havebeen modified, the modified elements being denoted by 62′ and 68′,respectively. The valve seat 68′, formed about the periphery of an endof second bore 54 facing the first bore 48, has an inwardly taperingprofile. Similarly, annular valve member 62′, which in one exampleembodiment is formed from a plastic material, has a tapering outersurface facing valve seat 68′. Thus, valve seat 68′ and valve member 62′have corresponding opposing truncated-conical or frusta-conical surfacesthat cooperate when in the closed position to seal valve first bore 48from valve opening 53. The use of sloping or tapering engagementsurfaces provides a larger engagement interfaces between valve member62′ and valve seat 68′ than if the engagement surfaces are simply atright angles to the first bore and valve opening axes. The valve member62′ defines an axial cylindrical opening 146 through which thermal motorshaft 66 passes. In an example embodiment, a lip or flange 148 isprovided about a periphery of the opening 146 on a side thereof thatfaces away from the second bore 54, thereby providing a longer interfacebetween member 62′ and shaft 66, making it more difficult for fluid toleak between shaft 66 and valve member 62′. Valve member 62′ and 68′ mayprovide an improved seal in some applications. The relatively largeinternal surface that defines opening 146 provides a large contact areaalong shaft 66, reducing the chance for binding of the sealing valvemember 62 as it moves along the shaft.

Turning again to the example embodiment of the by-pass valve shown inFIGS. 1-4 and 7, although the return spring 70 has been shown as havingcoils that continuously increase in diameter from the first end 40 tothe second end 42 of the spring 70, in some example embodiments the coildiameter does not steadily increase from the first end to the secondend. By way of example, FIG. 15 shows an alternative return spring 70′that is used with valve assembly 38 in some example embodiments. Asindicated by dashed line 150, the return spring 70′ has an hourglassshape in that as the axial distance increases from the first end 40, thecoil diameters first get smaller and then increases in size to thesecond end 42 of the return spring 70′. Thus, along a first axial lengthof the return spring 70′, coils of the return spring 70′ have decreasingdiameters as the distance of the coils from the first end 40 increases,and along a second axial length of the return spring 70′ that is furtherfrom the first end 40 than the first axial length, coils of the returnspring 70′ have increasing diameters as the distance of the coils fromthe first end 40 increases. Such a configuration can in someapplications facilitate the flow of oil through the spring coils withreduced flow resistance, especially high viscosity oil at lowtemperatures, and also facilitate the passage of oil through the coilsat higher temperature when actuation of the thermal element causes thespring 70′ to compress.

FIGS. 16 and 17 show another cap configuration for closing the assemblyopening 81 in housing 46. The cap 160, which may be used in any of theabove described configurations, is formed from a resilient material(which can be plastic), such that cap 160 can be inserted, with someradial compression occurring to it, through the assembly opening 81 inthe housing 46. Thus, the opening 81 has a smaller diameter than the cap160. FIG. 16 shows the cap 160 in a first position “A” in which the cap160 is just starting to be inserted through opening 81, and in a secondposition “B” in which the cap 160 is inserted into an upper end of thefirst bore 48.

The upper end of first bore 48 includes an annular recess 162 into whichat least a portion of the cap 160 expands once the cap has been insertedinto place. Once inserted, the cap 160 is effectively permanently lockedin place. The recess 162 terminates at an upper annular shoulder or seat164. At a lower end, the recess 162 has an inwardly tapering annularwall 166 that opposes seat 164 at an oblique angle. The cap 160 has anupper surface 168 for engaging seat 164. The cap 160 has an uppercylindrical portion 170 which is received within recess 162, and has alower tapering annular wall portion 172 for engaging the wall 166 ofrecess 162. Once the cap 160 is inserted into position, its uppersurface 168 engages seat 168 and its lower tapering wall portion 172engages correspondingly tapered recess wall 166, thus placing the cap160 under axial loading to prevent movement of it relative to housing46. In an example embodiment, the cap 160 is sufficiently preloaded(i.e. compressed between surfaces 164 and 166) after insertion such thatits stays secure throughout various temperature variation and otherstresses that occur during use and the lifespan of the valve. In someembodiments, cap 160 may include one or more annular protrusions orbeads 174 formed on tapering portion 172 for providing further sealingbetween the cap 160 and housing 46. Alternatively, one or more annularbeads 174 could be located on the wall 166 in addition to or instead ofon portion 172. In one example embodiment, one annular bead 174 islocated on portion 172.

Having described example embodiments of the invention, it will beappreciated that various modifications in addition to those already setforth can be made to the structures described above. For example, insome embodiments either both or one or the other of the housing and capcould be made of materials other than plastic such as metal. A number offeatures have been described above, and different features andcombinations of features may be used in different embodiments.

The by-pass valves have been described above for use with an automotivetransmission oil cooler as the heat exchanger, but the by-pass valvescould be used with any other types of heat exchanger, such as fuelcooling heat exchangers, and in non-automotive applications as well.Other types of thermal actuators can be used than the wax-type actuator64. For instances, bimetallic or shape memory alloy thermal responsiveactuators could be used to move valve member. Further modifications tothe structures described will be apparent to those skilled in the art.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention. Accordingly, the scope of the inventionis to be construed in accordance with the substance defined by thefollowing claims.

1. A by-pass valve for a heat exchanger circuit, the by-pass valvecomprising: a housing defining communicating first and second borestherein, first and second main ports communicating with the first bore,and at least a further port communicating with the second bore, thesecond bore having a central axis and a peripheral valve seat about avalve opening facing the first bore; a temperature responsive actuatorlocated in the housing and having a reciprocating central shaft disposedalong said central axis, the central shaft having a closed end portion;an annular sealing member slidably mounted on the central shaft andextending outward from the central shaft to engage the valve seat and,together with the closed end portion, close the valve opening; biasmeans for urging the annular sealing member toward the valve seat; and acoiled return spring mounted in the housing for urging the central shaftclosed end portion to retract and open the valve opening, the returnspring having a first end connected to the closed end portion and asecond end engaging a spring support in the housing facing the firstbore, the return spring having a larger diameter at its second end thanits first end, wherein along a first axial length of the return spring,coils of the return spring have decreasing diameters as the distance ofthe coils from the first end increases, and along a second axial lengthof the return spring that is further from the first end than the firstaxial length, coils of the return spring have increasing diameters asthe distance of the coils from the first end increases.
 2. The by-passvalve of claim 1 wherein the housing includes a branch port forming withthe further port a branch port passage that communicates with the secondbore, the spring support being located in the branch port passage.
 3. Aby-pass valve for a heat exchanger circuit, the by-pass valvecomprising: a housing defining communicating first, second and thirdbores therein, first and second main ports communicating with the firstbore, and at least a further port communicating with the third bore, thesecond bore having a central axis and a peripheral valve seat about avalve opening facing the first bore, the third bore seriallycommunicating with the second bore, the second bore communicatingdirectly with the first bore, the second bore having a largercross-sectional flow area than the third bore; a temperature responsiveactuator located in the housing and having a reciprocating central shaftdisposed along said central axis, the central shaft having a closed endportion; an annular sealing member slidably mounted on the central shaftand extending outward from the central shaft to engage the valve seatand, together with the closed end portion, close the valve opening; biasmeans for urging the annular sealing member toward the valve seat; and acoiled return spring mounted in the housing for urging the central shaftclosed end portion to retract and open the valve opening, the returnspring having a first end connected to the closed end portion and asecond end engaging a spring support in the housing facing the firstbore, the return spring having a larger diameter at its second end thanits first end, wherein the spring support includes a peripheral springseat engaging the second end of the return spring, the peripheral springseat being located at a transition between the second bore and the thirdbore, where the third bore has a non-circular cross-sectional areatransverse to the central axis and the second bore has a circularcross-sectional area transverse to the central axis.
 4. The by-passvalve of claim 3 including a closure cap, the housing including anassembly opening located opposite the valve seat that is sealed shut bythe closure cap, the closure cap and housing being formed from plasticmaterials with the closure cap sealably joined to the housing.
 5. Theby-pass valve of claim 4 wherein the closure cap is joined to thehousing by ultrasonic welding, friction welding, adhesive bonding orsolvent bonding.
 6. A by-pass valve for a heat exchanger circuit, theby-pass valve comprising: a housing defining communicating first andsecond bores therein, first and second main ports communicating with thefirst bore, and at least a further port communicating with the secondbore, the second bore having a central axis and a peripheral valve seatabout a valve opening facing the first bore; a temperature responsiveactuator located in the housing and having a reciprocating central shaftdisposed along said central axis, the central shaft having a closed endportion; an annular sealing member slidably mounted on the central shaftand extending outward from the central shaft to engage the valve seatand, together with the closed end portion, close the valve opening; biasmeans for urging the annular sealing member toward the valve seat; and acoiled return spring mounted in the housing for urging the central shaftclosed end portion to retract and open the valve opening, the returnspring having a first end connected to the closed end portion and asecond end engaging a spring support in the housing facing the firstbore, the return spring having a larger diameter at its second end thanits first end, wherein the spring support includes a discrete supportmember inserted into the housing and extending across the second boreand having a flow opening therethrough, and wherein the spring supportincludes a substantially planar disk having a plurality of flow openingsformed therethrough.
 7. The by-pass valve of claim 6 wherein the annularsealing member and the valve seat have sloping surfaces that cooperatewhen in a closed position.
 8. A by-pass valve for a heat exchangercircuit, the by-pass valve comprising: a housing defining communicatingfirst and second bores therein, first and second main portscommunicating with the first bore, and at least a further portcommunicating with the second bore, the second bore having a centralaxis and a peripheral valve seat about a valve opening facing the firstbore; a temperature responsive actuator located in the housing andhaving a reciprocating central shaft disposed along said central axis,the central shaft having a closed end portion; an annular sealing memberslidably mounted on the central shaft and extending outward from thecentral shaft to engage the valve seat and, together with the closed endportion, close the valve opening; bias means for urging the annularsealing member toward the valve seat; and a coiled return spring mountedin the housing for urging the central shaft closed end portion toretract and open the valve opening, the return spring having a first endconnected to the closed end portion and a second end engaging a springsupport in the housing facing the first bore, the return spring having alarger diameter at its second end than its first end, wherein the springsupport includes a discrete support member inserted into the housing andextending across the second bore and having a flow opening therethrough,wherein the spring support has a cup-like profile, including an annularwall having an outer peripheral flange at a first end thereof and aradially inwardly extending flange at an opposite end thereof, theopposite end being located further from the first bore than the firstend thereof, the peripheral flange engaging the support surface aboutthe periphery of the second bore, the second end of the return springbeing received within the annular wall and engaging the inwardlyextending flange, the at least one flow opening being defined by theinwardly extending flange.
 9. The by-pass valve of claim 8 wherein theannular wall tapers inward from the first end of the spring support tothe opposite end thereof and flow openings pass through the annularwall.
 10. A by-pass valve for a heat exchanger circuit, the by-passvalve comprising: a housing defining communicating first and secondbores therein, first and second main ports communicating with the firstbore, and at least a further port communicating with the second bore,the second bore having a central axis and a peripheral valve seat abouta valve opening facing the first bore; a temperature responsive actuatorlocated in the housing and having a reciprocating central shaft disposedalong said central axis, the central shaft having a closed end portion;an annular sealing member slidably mounted on the central shaft andextending outward from the central shaft to engage the valve seat and,together with the closed end portion, close the valve opening; biasmeans for urging the annular sealing member toward the valve seat; and acoiled return spring mounted in the housing for urging the central shaftclosed end portion to retract and open the valve opening, the returnspring having a first end connected to the closed end portion and asecond end engaging a spring support in the housing facing the firstbore, the return spring having a larger diameter at its second end thanits first end, wherein the spring support includes a discrete supportmember inserted into the housing and extending across the second boreand having a flow opening therethrough, wherein the spring support has acup-like profile, including an annular wall having an outer peripheralflange at a first end thereof and an annular spring seat at an oppositeend thereof, the opposite end being located closer to the first borethan the first end thereof, the peripheral flange engaging the supportsurface about the periphery of the second bore, the second end of thereturn spring being received within the spring seat.